Compact VirtualBox Disk Images
- author:: Nathan Acks
- date:: 2022-01-28
(1) Zero out free disk space on the guest:
WINDOWS: Disable the paging file (Settings > System > About > Advanced system settings > Advanced > Performance > Settings… > Advanced > Virtual memory > Change…), clean all temporary files (C: > Properties > Disk Cleanup), defrag (defrag C: /FreespaceConsolidate /Verbose), and then zero out free space with SDelete (sdelete -z C:).
LINUX:
sudo dd if=/dev/zero of=/temp.zeros bs=4096k
sudo rm -f /temp.zeros
(2) Compact the disk image on the host:
vboxmanage modifymedium /path/to/image.vdi --compact
Remember to turn the paging file back on after compacting the drive (for Windows guests)!
Note that this only works on a disk image without any snapshots.